(1.) Field of the Invention
The present invention relates to an improved coupling (10) adapted to be embedded in concrete (101). In particular, the present invention relates to a coupling having regularly spaced concentric rings (11c) on the outside (11b) of the coupling which provide a water tight seal with the concrete and which provide a means for adjusting the height of the coupling prior to installation by cutting to conform with the concrete pour upper surface (101a or 101b) to provide a flush fit.
(2) Prior Art
The prior art in my U.S. Pat. No. 4,261,598 describes an improved coupling. This coupling works very well but allows water to seep between the interface of the outside wall 13 of the tube 11 and the concrete 300. Further each pour of cement 300 requires a different height extension 100 with or without water closet flange 400. With my earlier coupling, solvent welding of the tube 11 pipe to the coupling was necessary for extension which required additional effort and resulted in a joint which might leak. Finally, my earlier coupling provided no protection from melting in case of fire.